Process of producing composite dental plates



Patented Dec. 31, 1935 PROCESS OF PRODUCENG COMPOSITE DENTAL PLATES Stefan Loos, Vienna, Austria "No'Drawing. Application May 2, 1932, Serial No. 608,861. In Austria April 2, 1932 Claims.

quired to fit closely and accurately upon an intricately uneven foundation surface, such as in particular the dental plates on which false teeth are mounted, the proposal has already been made at diiferent times to produce such bodies by a galvanic process, that is to say by electrolytic deposit. The materials used in this connection are primarily the precious metals or their alloys, but it is a peculiarity precisely of the precious metals, for example gold, that with the galvanic method of production hitherto employed these metals can only be deposited with great difficulty and then only to such a slight extent that a plate of the required thickness cannot be obtained. Further, 20 it has not been possible hitherto to impart to plates obtained by electrolytic deposit the degree of, hardness required, for example, in palate plates. The present invention provides a method by which it is possible to produce alloys, more particularly of the precious metals, in any desired thickness and with any desired degree of hardness by electro-deposition or by the known metal spraying process. The method consists essentially in the deposition of the components destined to form the alloy individually and consecutively in thin layers. Experience has shown that as a rule alloying takes place to a certain extent between the individual layers during the process of deposition, particles of the layer being deposited passing in between particles of the previously deposited layer. In certain cases the alloy thus formed between the individual layers will sufiice for the purpose in view; as a rule, however, after the termination of the electrodeposition or 40 spraying on of all the layers the metallic body thus obtained will be subjected to a heating process in order to produce as intimate an alloy as possible. The thinner the individual layers are of which the finished metal body is to be built 45 up the easier it is to carry out the alloying process. If therefore, for example, it is desired to produce an alloy of gold, silver, and copper it Will not as a rule be advisable to build up this alloy of one layer each of these three metals, which layers would need to be comparatively thick, but of a plurality of layers of each ingredient metal, the layers of the same metal being preferably applied not consecutively but alternatingly with those of the other metals.

By this method it is possible to vary within wide limitsthe nature and composition of the metallic body produced, as regards for example fineness and hardness, in its thickness, by varying the nature, order, number and thickness of the layers forming the individual components of the alloy and being deposited in the course of building up the required body to its full thickness.

The described method is of far-reaching significance for the manufacturing of metallic alloys in general, but it has proved to be particularly'advantageous for the manufacturing of plates with intricately varied or uneven surfaces, such as for example dental plates. These plates are required to fit closely and accurately over the intricately uneven surface of the jaw and of the oral cavity, and at the same time they must be impervious to chemical action and highly resistant to mechanical strains. Apart from certain substitute materials (such as for example'chromium-plated steel) the only materials from which plates of the described order can satisfactorily be made are the precious metals, since these metals are chemically indifferent to the action of the substances with -which such plates are brought in contact. These metals, for instance gold, in the pure state are, however, too soft to permit of being used for palate plates, so that it is necessary to fall back on alloys of the precious metals for this purpose. As described above, such alloys can be produced by the method according to the present invention, in any desired degree of hardness, in a very simple, inexpensive, and at the same time absolutely reliable manner.

The procedure for the manufacturing of a dental plate can, for example, be as follows:

After a matrix of any desired type, preferably a metallic for instance a copper matrix, has been made from an impression of the patients mouth taken in a known manner, a thin precious metal leaf or foil is mechanically applied, e. g. polished on to this matrix. The sheet of precious metal foil, e. g. gold leaf, employed is somewhat larger than the finished dental plate, and is coated as to the portion of its surface outside the area of the finished plate with a covering substance, for instance wax. This covering has for its purpose, apart from the demarcation of the finished plate, to prevent any of the metal deposited from entering between the metal foil and the matrix, since in the latter event the detachment of the finished plate from the matrix would be attended with difliculty. The gold leaf is then lightly cauterized in a known manner and then placed in a gold galvanizing bath in which a thin layer of gold is deposited upon the foil. Upon this gold layer there is then deposited a thin layer of silver, and upon the latter a layer of copper. Further layers are then deposited, for example in the order silver, gold, silver, copper, silver, gold, coplarly upon how it is desired that the precious.

metal content and the varying degrees of hardness be distributed over the thickness of the the galvanic deposition itself.

plate. It has proved advisable to carry out the method in such a manner that the degree of fineness is highest in the portions of the plate nearest the surfaces, and decreases from both surfaces towards the middle of the plate. That is to say at and in the neighbourhood of the surfaces of the plate the layers of precious metal will be more numerous and/or thicker than in the middle of the plate.

During the galvanic process itself the individual thin layers deposited become to a certain extent alloyed. The plate is then removed from the matrix, for which purpose the sheet of precious metal foil applied to the matrix before commencement of the electrolytic process is cut through along the line marked by the contour of the wax coating, and then set in any one of the embedding substances known to dental practice. The plate is then heated for the purpose of completing the alloying process initiated by After cooling-off the plate is finished and ready to be employed in the usual manner for the mounting of artificial teeth, and possesses all the properties required of a dental plate for the purpose described.

The deposition of the individual layers of the alloy can also be effected by Schoops metal spraying process instead of electrolytically, as described above, It is essential in this case also that there be employed as the immediate carrier of the deposited, i. e. sprayed-on, layers a sheet of precious metal foil which is readily detachable from the metallic matrix used.

What I claim, is:

1. A process of producing composite metal plates for dental purposes of a plurality of layers of metals selected from the group consisting of copper, silver and gold, which comprises forming a copper matrix from an impression of the patients mouth, mechanically applying a gold leaf to said matrix, the area covered by said gold leaf being somewhat larger than the finished dental plate, coating the portion of the surface outside the area of the finished plate with wax to demark the finished plate and to prevent any of the metal deposited entering between the gold foil and the matrix, cauterizing the gold leaf upon the copper matrix, depositing a thin layer of gold upon the gold foil, then depositing a thin layer of silver upon the deposited gold layer, and then depositing upon the thin silver layer a thin layer of copper and continuing said deposition of alternate layers of said metals until the required thickness of the plate is obtained, the final layer being a gold layer and placing upon said final gold layer a sheet of gold leaf, removing the plate from the matrix and cutting the plate along the line marked by the contour of the waxed coating and then heating the plate for causing the metal layers to alloy together.

2. The process of claim 1 in which the metal layers are electrically deposited upon each other.

3. The process of claim 1 in which the metal layers are deposited by being sprayed upon each: other.

4. The process of claim 1 in which the metal layers are deposited in the following order, namely, gold, silver, copper, silver, gold, copper, silver,

gold, copper, silver, gold and so forth until the-.40

required thickness of the plate is obtained.

5. The process of claim 1 in which the gold layers are made more numerous or thicker at the surface of the plate than at the middle of the plate,

' STEFAN LOOS. 

